歷來，唐代思想的研究者多以韓愈的〈原道〉、〈原性〉、及李翱的《復性書》作為其後引發宋明性理學勃興的代表作。當時，佛道兩教在思想界具有極大影響力，仕宦與否的關鍵雖取決於寫作詩文的能力，若能具備儒學知識則更佔優勢，惟儒學在三教之中則呈相對劣勢。韓愈與李翱力倡排抑佛道、獨尊儒教，直到北宋後半葉仍引來極大的反響。由此觀點，韓愈與李翱對於儒教之復興貢獻極大，固無庸置疑。然而，若就中國思想史整體而言，或就唐代思想史、唐宋思想史而言，此種評價便必須受到修正。究竟韓愈與李翱的思想在唐代後半具有多大的影響力，必須按照具體資料重新檢討，同時也必須針對唐代後半期、特別是唐末葉的思想狀況作具體分析。基於此，筆者認為陸希聲及其《道德真經傳》，尤其值得矚目。 陸希聲的《道德真經傳》，不僅主張符合孔子、老子之教，其特色是透過五經或四書，尤其是《易傳》和《禮記》《中庸》、《樂記》等篇章來重新解讀《道德經》。筆者認為，雖然其序文極力強調老子之教涵括了伏羲、文王、孔子等儒家三聖之教，實質上卻在不知不覺中堅守恢復儒學主體性之立場。只是它在展開論述時，頻頻使用了「體‧用」、「理‧事」「實‧權」等來自佛教之三論、天台教學、或隋唐道教教理學 (例如《道教義樞》)等之相對概念，可見佛道兩教的思維方式在當時的思想界已經成為主要的基幹。 陸希聲重新架構了「復歸」思想，他主要本於老莊的「復歸」，以及《周易》的「復」、「性情」等思想，並參考李翱的《復性書》的主張，大幅擴充了上述理論的貧弱性，更以佛道兩家所習用的「權‧實」邏輯加以重構。年代稍後的強思齊《道德真經玄德簒疏》、杜光庭《道德真經廣聖義》諸書，表面上主張三教融合，但其解釋始終以道德思想為主軸，理倫體系也存在若干問題。相較而言，陸希聲的《道德真經傳》則實際以儒家思想解釋《道德經》，他使用佛道兩教共用的語彙來展開論述，而且較當時可見的其他著作來得更為全面且有體系。

Historically, most scholars have taken Han Yu's Yuandao and Yuanxing and Li Ao's Fuxing shu as the representative works marking both the culmination of Tang thought and the initiation of the Neo-Confucian xingli teaching of the Song and Ming dynasties. During this period, when ability at poetic composition was among the deciding factors for government appointment, while Buddhism and Daoism were both extremely influential among intellectuals, those who could fully express Confucian learning were adcantaged as Confucianism was prominent among the three teachings. The denigration of Buddhism and Daoism and exaltation of Confucianism by Han Yu and Li Ao remained influential and repeatedly echoed until the latter half of the Northern Song. By this reasoning, Han Yu and Li Ao's contribution to the revival of Confucianism was undoubtedly great. However, from the perspective of Chinese intellectual history, or even jist from the perspective of Tang or Song thought, this evaluation needs some reconsideration. In order to examine Han Yu and Li Ao's influence during the latter half of the Tang we need to critically re-evaluate some contemporary material. We must also reconsider the intellectual situation during the latter half of the Tang, and in particular, the final years of the dynasty. Based on these considerations, the author finds Lu Xisheng's Daode zhenjing zhuan especially worthy of study. Lu Xisheng's Daode zhenjing zhuan not only advocates the equivalence of the teachings of Confucius and Laozi. Of particular interest is its re-reading of the Daode jing from the perspective pf the Five Classics and Four books, the Zhongyong and Yueji chapters of the Liji in particular. The author considers that despite Lu Xisheng's insistence in his preface that Laozi's thought contained the teachings of the three Confucian sages, Fuxi, king Wen and Confucius, he actually, perhaps unconsciously, adopted a subjective Confucian perspective. However, as in the unfolding of his argument Lu Xisheng frequently uses terms such as 'Substance and function ti/yong''pattern and phenomena li/shi''substance and expedience shi/quan' borrowed from the Buddhist Sanlun school, and notions developed in Tiantai teachings and Daoist thought of the Sui-Tang period (such as expressed in Daojiao yishu). Clearly, Buddhist and Daoist concept and patterns were already important elements within the intellectual world of the period. Lu Xisheng's re-structuring of the notion of 'return fugui' was based on the one hand on the 'fugui' concept in Lao-zhuang thought, the ideas of 'fu' and 'nature and emotion xingqing' of the Yijing. On the other hand relying on Li Ao's Fuxing shu he greatly elaborated upon the weaknesses of the above theories by combining them with the logical concept of 'shi/quan' favored by the Buddhists and Daoists. Slightly later workd, such as Qiang Siji's Daode zhenjing xuande zuanshu and Du Guangting's Daode zhenjing guangsheng yi while superficially advocating the merging of the three teachings were fundamentally Daoist in their explanations and annotations. Their theoretical stance thus remained problematic. In comparision, Lu Xisheng's Daode zhenjing zhuan actually used Confucian thinking to explicate the Daode jing while using Buddhist and Daoist terminology to develop his arguments. He thus produced a more complete system of thought than his contemporaries.